Catalytic conversion of hydrocarbons



Dec. 8, 1942. A. B. DORAN CATALYTIC CONVERSICN OF HYDRQCARBONS FiledNov. 24, 1939 m/ws/vroel ALBERT 5. DQRAN 3v H%IECH F0; 75/? aHARR/J FORTHE F/QM A TTOQ NE VJ Patented Dec. 8, 1942 UNITED STATES PATENT OFFICECATALYTIC CONVERSION OF HYDROQARBONS AlbertB. DoramLosAiigeles, Calif,assignorto Dorex, Ina, Reno, blew, a corporation of Nevada ApplicationNovember 24, 1939, Serial No. 305,901

I '1 Claims. This invention relates to the conversion of hydrocarbons,and more particularly to amethod and catalyst for the conversion andreforming of hydrocarbons.

, Hydrocarbon conversion processes have wide drocarbons, includingreforming thereof, and in particular to provide such a process adaptedto produce large yields of highly alkylated or cyclized products havingsuperior anti-knock properties when used as a motor fuel and also havingsuperior solvent properties.'

I have discovered that the desired conversion reaction may be inducedand/or guided by a catalyst comprising a heavy metal salt of an acidicoodde of manganese, more particularly heavy metal manganites andpermanganites.

It is an object of the present invention to provide catalysts of thetype described and to provide a method for their eiliclent utilizationin the catalysis of hydrocarbon conversions.

It is a further object of the present invention to provide a catalyticconversion process of the kind described in which variable proportionsof auxiliary gases, such as air, steam, carbon dioxide, or theirequivalents, as hereinafter described, are employed to condition thecatalyst and/or maintain it at a high level of activity and/or to reactwith the hydrocarbon particularly for the purpose of forming oxygenatedintermediates adapted to yield ultimately the desired reformedhydrocarbons, and/or to suppress undesired reaction and to prevent theformation of undesired deposits.

Further objects and aspects of my invention will become apparent in thefollowing description of my process, particularly as made with referenceI to the drawing, which is a schematic representation of equipmentsuitable for carryi g out my process.

Referring to the drawing, I0 is a storage vess containing thehydrocarbon stock which it is desired to convert. This stock istransferred by means of a transfer pipe I l to a pipe still I! where itis heated to-a temperature suflicient to induce substantialvaporization, which vaporization may take place either in the pipe stillor an expander or flash chamber l3 into which the heated efliuent fromthe pipe still I2 is conducted by means of a transfer pipe M. Thevaporized hydrocarbons in expander II are conducted by means of atransfer pipe I to a mixer l6 where the vapors may be admixed withsuitable proportions of auxiliary gases, suitably air supplied through apipe I1 and containing a small proportion of carbon dioxide, if desired,and recycled gases containing gaseous oleflns suitably supplied througha transfer pipe i8. These additional materials are preferably heatedprior to their admixturewith the hydrocarbon vapors as by flow throughpreheaters Ila V and l8a, respectively, as indicated.

The admixed vapors are then passed through a series of externally heatedcatalyst chambers 20 filled with contact material comprising themanganite or permanganite catalysts as herein described. The catalyticmaterial is preferably employed in the form of discrete particles whichv leaves substantial pore space for the flow of gases therethrough andif desired the catalyst may be carried by an inert supporting materialsuch as alumina which may be formed in such size and shape as to insurethe eflicient contact of the catalytic material with the gases whilepermitting the ready flow of gases through the catalytic bed.

The catalytic vessels 20 as well as the preheaters lla and I80. may bevery conveniently heated by positioning them as indicated in a furnace25 constructed of heat-resistant walls 26 and having a burner 21 and abaflie 28.

' The hot furnace gasesare passed downwardly over successive converters20 so that the flow of the combustion gases is concurrent with the flowof vapors through these catalytic vessels whereby the maximum heat isimparted initially to the coolest portion of the vapor stream.

The flue'gases from the furnace 25 may be very advantageously withdrawnthrough a duct 29 and employed to heat the pipe still I! as indicated.The eiiiuent from the catalytic converter oxide, suitably by means ofknock-back coil 13. a The heavier constituents are liquefied andfractionated out. If desired the heavier high-boiling fractionswithdrawn,through pipe 34, which will normally consist in part at least.of heavy unconverted hydrocarbons, may be transferred by means of a pipe35 and apump 36 back into transfer pipe II for recyclingthrough theprocess. This recycle stock mayadvantageously include any liquidresidues left in expander I! which may be transferred by means of a pipeI! to the recycle pipe 35, q

The overhead from the bubble tower 3| is withdrawn by means of a pipe 40and this stream may be supplemented if desired by a liquid sidecutwithdrawn through a pipe 4|, these cuts be-- ing commingled ina header42 leading to a mixer 48. Air, together with a small proportion ofcarbon dioxide, if desired, may be introduced into mixer 43 by means ofa pipe 44 and a pipe 45 servesto introduce superheated steam. Both ofthese auxiliary gas streams are best provided with preheaters asindicated at 440 and 45a respectively.

I The eiiluent from mixer 43 is brought by means of a transfer pipe 50to a pump in which the vapors and mixed gases are brought up to apressurevcorresponding to that which it is desired to maintain in thesucceeding conversion stages. The pressured eflluent from pump 5| passesby means of a transfer line 52 into a second converter constituted bycatalytic chambers 53. These chambers are filled with catalytic contactmaterial-such as described above and are arranged to be externallyheated.

The eiliuent from catalytic chambers 53 is brought by means of atransfer pipe '55 to a third mixer 56 in which it may be mixed withstill further quantities of superheated steam, and/or auxiliary gases,such as air or carbon dipipes 51 and '58 branching fromlines 44 and 45.

- which may be constituted by unconverted and/or Pump 85 may also takedirect bottoms from the tower '14.

polymerized hydrocarbons may be withdrawn as a liquid fraction from thebottom of fractionating tower It by. means of a pipe II; A portion ofthis withdrawn'liquid or all may be picked up by means of a pump 82 andtransferred through a pipe "to the upper portion of'the scrubbing towerI! to serve as a washing liquid-therein.

The washing liquid and condensate accumulating inthebottomof thescrubbing tower 12 may be withdrawn through a pipe 84 and transferred bymeans of a pump 85 into the recycle pipe 3|. suction on the A bleed pipe90 is provided for recycle pipe II by means of which any desired portionof the recyclestock may be diverted from the system.

In addition to the liquid recycle, all or a portion of the gases may berecycled. Thus the\.gases in pipe 18 may bepicked up by means of a pump95 and conducted by means of a pipe 96 to the preheater l8a. fIfit isnot desired to recycle all of the gases, ,a portionthereof may beremoved from the system by means of a bleed pipe I1. The waste gas mayadvantageously be subjected to a vapor recovery process.

In manyinstances it is desirable to recycle only the heavier gases,leaving the lighter fixed gases such as methane to be bled from thesystem. For this purpose the recycle gases in pipe 96 may be divertedinto a pipe I00, pressured by a pump lfll, and fractionated in afractionating column I02. The liquefied gases may be withdrawn from thebottom of the column I02 and returned to the recycle system by means ofa pipe I03, while the fixed gases are removed from the top of the columnby means of a pipe I04.

The auxiliary gases, including steam, an oxy gen containing or oxidizinggas such-as oxygen, air, oxides of nitrogen, etc., and if desired amodifying gas such as carbon dioxide, may be conducted to the respectiveheaters by any suitable piping system. In the system shown air orTheefliuent from the mixer 56 iaconducted by means of a pipe 51 into athird set of externally heated catalytic converters 59 containing asdescribed above .a manganite or permanganite catalyst. Catalyticconverters 53 and I9, as well as preheaters 44a and a, may be ad--vantageously heated in a single furnace 60 simigaseous material isconducted by means of a pipe 15 to a condenser 16. The mixed condensateand gases are withdrawn from the condenser I8 to a gas separator 11 fromwhich the gas is withdrawn by means of a pipe 18 and from which thecondensed hydrocarbon fraction may be withdrawn by means of a pipe 19for storage or further refining.

The fractionating tower 14 may be advantageously provided with a refluxcondenser 80 which may be cooled if desired by water circulating fromthe'condenser 16. The heavier fractions which are not desired in thefinal product and similar oxidizing gas is supplied under pressure to amain pipe H0. Air is passed from pipe llll into a pipe the pipe 2leading to preheater Ila. A valve 3 controls the rate of admission ofair to pipe H4, whence it is led to preheater 44a.

As a rule the inert or modifying gas such as carbon dioxide can beadvantageously commingled with the air in the desired proportions priorto heating. Thuscarbon dioxide maybe supplied under pressure to a pipeH5, and maybe admixed in desired proportion with the -air in pipes illand ll4bymeans of valves H6 and Ill respectively.

Steam may be generated by any suitable source and conducted to preheater45a by a pipe I It.

The catalysts which I employ comprise basic oxides of heavy metals inassociated or compound form with an acidic oxide or oxides of manganese,more particularly acidic oxides in manganese is trivalent ortetravalent,

as in manganites and permanganites.

By the term manganite I have'here particular reference to salts ofmanganous acid HMnOzin which the manganese is trivalent. By the termpermanganite I have reference to salts of permanganous acid HaMIlOs inwhich the manganese is tetravalent. For example, I may employ as mycatalyst nickel manganite Ni(MnOz) 2. I may also employ polymanganitesalts b'est formulated as a mixed oxide, for example NiO.(MmOa-)n inwhich n is a simple integer that can be as high as 10- or H2 at a ratecontrolled by valve Ill, 1

which the more. I may also employ nickel permanganite NiMnO or nickelpoly-P rmanganite NIOJMnOa) 11. again being a simple integer.

These compounds may be variously produced, suitably by digestion orcontactoi the corresponding alkali metal salt with an aqueous solutionor art, typically by alkaline reduction of a higher valent manganesecompound. If desired, the reduction can be accomplished in the presenceof a dissolved heavy metal 'salt whereby the heavy metal manganite orpermanganite may be produced directly.

According to the method of preparation, a'

manganite, permanganite, or mixed manganite and permanganite salt may beobtained. Also there may frequently be more or less uncombined manganesesesquioxide or dioxide in anhydrous or hydrated form. I may employ allof such mixtures as catalysts, although in general the most activecatalysts are those which contain a substantial heavy metal content.

The catalyst will. normally be obtained in flnelydivided or precipitatedform and for, its most efficient utilization it is frequently desirableto employ it in association with a supporting agent, suitably a granularceramic material which may be coated with the wet catalyst and thendried. Various other methods of catalyst separation may also beemployed; for example, precipitation of the catalyst on a supportingagent.

Various heavy metals may be incorporated in my catalyst either singly orin mixture, such as nickel, chromium, zinc, copper, and the like. I findit particularly-advantageous to employ as the heavy metal component,those metals which in the reduced state have a recognized catalyticactivity for hydrogenation processes, typically nickel.

While I do not wish to be bound by any theory as to the preciserelationship between the activity of my catalysts and their molecularstructure, apparently at least a portion of their activity is due to therelatively large number of oxygen ions which are in association with apotentially multivalent manganese ion. I believe that this makes itpossible for the catalyst to receive or discharge a number of oxygenatoms particularly in the complex poly-manganitesand poly-permanganites,whereby these compounds are very effective as a carrier catalyst foroxidative reaction. In addition, the catalytic activity is contributedto or promoted by the presence of the heavy metal ions in the basicportion of my catalyst possibly in some manner connected with theirknown hydrogenating and dehydrogenating activities. In practice,however, it is observed that the heavy metal compound of my catalyst isin a very stable -form not subject to substantial oxidation orreduction.

I have discovered that catalysts o! the type described have the verygreat advantage of beingable to cause numerous types of hydrocarbonconversion reactions to take place in one reaction zone, such asdehydrogenation, oxida-- tion, alkylation, isomerization, cyclization,polymerization, and aromatization, these reactions being illustrated ingreater detail hereinbelow..

4 3 Another very great advantage resident in these catalysts is theirability to be. continually reactivated during the process. Thiscontinued activity is due in part to the ability of the catalyst to takeup oxygen from the mixed stream 01' oxygen and hydrocarbon vapors,whereby the catalyst is continually maintained in a fully oxygenated andactive form and in spite of any temporary reduction that be occasionedby reactions taking place on its surface.

The catalyst also has the'ability to keep itself clean and tree frommasking carbon deposits when employed in an atmosphere comprisingoxygen, steam, carbon dioxide, or mixtures of these three gases. Iattribute this self cleansing action to the ability of the catalyst topromote the combination of any'deposited carbon with oxygen to producecarbon monoxide or carbon dioxide, or to its ability to promote thewatergas type or reaction between the deposited carbon andthe steam, orits ability to promote a reaction between carbon and carbon dioxide toproduce carbon monoxide, or ,to promote all or these reactionsgenerally.

The function of the auxiliary gases as employed in my process is notlimited to their cleansing efiect on the catalyst. Thus the steam mayenter directly into various reactions with the hydrocarbons ortheiroxygenated intermediates, particularly hydrolytic reactions ashereinafter illustrated. The oxygen contained in the air or other oxygencontaining gas may enter directly into reaction with the hydrocarbonseither as a surface catalyzed reaction, or with the catalyst serving asan oxygen carrier whereby oxidative dehydrogenation of the hydrocarbonsmay be obtained and various oxygenated The preferred method of workingmy process is to start with a petroleum hydrocarbon charging stockhaving a maximum boiling point preferably lower than 750 FQandcontaining hydrocarbons having preferably not more than 18 carbon atomsin a single chain, such as octadecane or lower members of the paraffln'series.

This stock is vaporized and admixed with air, oxygen, or variousoxidizing gases such as ozone or nitrogen oxide to the extent of about5% of the total volume of gases, 1. e., 5% of oxygencontaining gases and95% of gaseous petroleum vapors. If desired, a small proportion ofcarbon dioxide may also be added.

When this mixture is passed over the catalyst at a temperature from 800F. to 1500 F., the

precise temperature depending upon the nature of dehydrogenation,together with more or less v where immediately oxidized to form water.This may be represented by the equation 7 M.1:Mnuoz+RCH2CH2-R IM=MnvO1|-'i+R-CH=CHR+H20 MxMh Oz' represents symbolically the complexheavy metal manganites and/or permanganites employed as catalysts. Thisreaction illustrates the irreversible character of the dehydrogenationobtained as well as typifymg the role of the catalyst as an oxygencarrier which is continuously regenerated.

Various other reactions may also occur in the first and subsequent zoneswhich are discussed more fully hereinbelow. The eilluent from the firstzone may comprise some unconverted heavy hydrocarbons as well as someheavy polymers, this heavy material being fractionated out and recycledback through the first unit to obtain further conversion into lowerboiling material.

The petroleum hydrocarbons; and hydrocarbon gases passing into thesecond stage of operation may be mixed with superheated water vapor toform a mixture usually comprising from to cnecawm-on-enr-onr 15% watervapor and from 85% to 95% hydrocarbon vapor. The-amount of superheatedsteam which is added at this point will depend in part on the amount ofwater vapor formed in the first reaction zone as given in theillustration above. I may also add'additional quantities of oxygenbearing gases in the second unit for complete conversion of thehydrocarbons to the desired product. These admixed vapors are thensubjected to intimate contact with the catalyst in the second zone. Theoperating temperatures in this zone may be from 800 F. to 1800 F., and athe operating pressure in this and subsequent zones may befromatmospheric up to 20 atmospheres or more, depending upon the type ofproduct required and the nature of the charging stock.

I have found it advantageous to have from two to seven reaction zoneswhich may be maintained at different pressures and temperatures.Depending upon the type of charging stock and the nature of theproductdesired, the conditions in each zone may be varied to optimum fordehydrogenation, oxidation, cleavage, alkylation, cyclization, and thelike. e

As in purely thermal cracking, cleavage of the high molecular weightparafilns to lower molecular weight parafiins and olefins may take placethroughout the entire process. In the presence of the catalyst, however,the time and temperature necessary for these reactions are considerablyreduced. Thus I have found that in the presence of my catalyst normaloctane decomposesto form short parafiin'chains and long olefin chains atrelatively low temperatures. With longer chain hydrocarbons the cleavagebecomes more complicated, as illustrated by the following reactionsR-CHr-CHECHz-CHr-CHr-R These oxides or peroxides may decompose directlyto form a more highly unsaturated molecule, or in the presence of watervapor and the catalyst they may hydrolyze to form polyhydrlc alcohols orthey may be split to form aldehydes. Typical reactions are -indicatedbelow:

Aldehydes may also-be produced by directoxidation of unsaturates,typically as follows:-

Ho=crr,+M,Mn,o.- Rcrr0+cm0+M.Mn,o.

I The highly reactive intermediate may be catalytically hydrated in thepresence of water vapor chain unsaturated alcohols and branch chain toform di-hydric alcohols, as exemplified below:

These di-hydric alcohols may then be partially or completely dehydratedto form branch diolefins respectively.

HaOH

n-cm-c-c=oH-R H! +H2O The general sequence normally followed in thebuilding up of highly branched unsaturated hydrocarbons according to thepresent process is given in the following set of equations:

unsaturates to form a cyclohexene derivative which is furtherdehydrogenated in the presence of the catalyst to an aromatic, thecondensation or ring closure of a singleunsaturate to form aftersubsequent dehydrogenation an aromatic hydrocarbon, and a thirdmechanism which takes place to some extent, namely, the formation ofacetylene by dehydrogenation of ethylene, and polymerization ofacetylene to form benzene.

It is possible that in someinstances the oxygen ring structure formed bycondensation of the formaldehyde with the unsaturates may decomposedirectly into diolefins without the intermediate hydration anddehydration.

I find that the formation of the aldehydes from oleflns and also thecondensation ofthe aidehydes with further olefins is displayed inhighest degree by oleiins containing 5 to 6 carbons, typically pentenesand hexenes. These reactions are also adequately displayed by lowermolecular weight oleflns, but with heavier oleflns there is anincreasing tendency for cleavage and/or polymerization reactions to takeplace. Polymerization processes are also catalyzed by my process asindicated below.

Cyclic and aromatic compounds are produced in my process by ring closureof unsaturates followed in certain instances by dehydrogenation. Thistype of reaction may take place in the presence of my catalyst withinthe temperature range of 800 F. to 1800 F. The aromatic compounds Myprocess is not only adapted to produce highly unsaturated and/orcyclized hydrocar bons, but also the yield is large, the yield ofconverted liquid being usually over The loss is represented largely bypermanent gases such I chain and cyclic compounds as produced by mywhereby alkylation according to the present proa substantial proportionoi. aromatics and alkylated aromatics.

The extensive alkylation of both the ope process leads to compoundshaving inherently superior combustion characteristics. The position oi.alkylatlon is also of importance in chain compounds, since the presenceof the alkyl group near the center oi. the chain endows the moleculewith much better anti-knock properties than when the alkyl group is nearthe end. The centrally alkylated type of hydrocarbon is preterentiallyobtained in my process inasmuch as the double bond of the saturatedhydrocarbons has a tendency to form near the center of the chain,

cedure attaches the alkyl groups near the center of the molecule. Thischaracteristic is mus H trated by the following equations which are Hdrawn to show the type oi! akylation, the position of the radicals, andthe position of the double bond in the chain.

Oleilns CHFCH-CEi-OHi-OHI l lsomsrization h l Alcohols double bond lhiitThrough oxide structure Through was Itmctmc cm-c-ou=oncm GHt-O-OH-OH-CH:

The catalytic conversion of paramn hydrocarbons in the presence of mycatalyst to produce oleflns and aromatic and cyclic compounds, as wellas short chain parafllns with alkylated branch chains is readilyaccomplished in the present process. The aromatic and cyclic com pounds,as well as tertiary parafllns, may be further alkylated in contact withmy catalyst by various reactions, some of which are typified below.

MMD OI m GE CEO catalyst mason catalyst ammo. a Y I Poulblc M I theclass of heavy metal manganites and per- The products of my process, inaddition to prohydrocarbons of superior anti-knock value comprising:contacting said hydrocarbons at elevated temperature with a catalystselected from the class or heavy metal manganites and permanganites,said contacting with the catalyst being made in the presence of-anoxidizing gas.

2. A process for converting hydrocarbons into hydrocarbons of superioranti-knock value comprising: contacting said hydrocarbons at elevatedtemperature with a catalyst selected from the class of heavy metalmanganites and permanganites, said contacting with the catalyst beingmade in the presence of steam.

3. A process for converting hydrocarbons into hydrocarbons of superioranti-knock valuecomprising: contacting said hydrocarbons at elevatedtemperature with a catalyst selected from manganites, said contactingwith the catalyst being made in the presence of carbon dioxide.

4. A process for converting heavy saturated hydrocarbons into lighterunsaturated hydrocarbons comprising: vaporizing said hydrocarbons;admixing said vapors with a minor portion of oxygen containing gas; andpassing said mixture over a catalyst selected from the class of heavymetal manganities and permanganites.

5. A process for converting hydrocarbons into hydrocarbons of superioranti-knock value, comprising: vaporizing said hydrocarbons; forming acommingled stream of said vaporized hydrocarbons and a minor proportionof air; passing said stream over a catalyst at a temperature of800-1500" F. to obtain olefinic vapors; admixing said olefinic vaporswith a minor proportion of steam; and conducting said admixture over acatalyst at a temperature of 800-1800 F., said catalyst in bothinstances being selected from the class of heavy metal manganites andpermanganites. v

6. A process for converting olefinic hydrocarbons into hydrocarbons ofsuperior anti-knock value comprising: admixing said hydrocarbons invapor form witha small proportion of steam; and conducting said mixtureat elevated temperatures over a catalyst selected from the classconsisting of heavy metal manganites and permanganites. v

7. A process as in claim 6, in which a minor proportion of air isadmixed with the hydrocarbon vapors and steam.

ALBERT B. DORAN.

